The present disclosure relates to systems and methods for percutaneous implantation of a prosthetic heart valve. More particularly, it relates to systems and methods for transcatheter implantation of a stented prosthetic heart valve.
Diseased or otherwise deficient heart valves can be repaired or replaced with an implanted prosthetic heart valve. As used throughout this specification, the terms “repair,” “replace,” and “restore” are used interchangeably, and reference to “restoring” a defective heart valve is inclusive implanting a prosthetic heart valve that renders the native leaflets non-functional, or that leaves the native leaflets intact and functional. Conventionally, heart valve replacement surgery is an open-heart procedure conducted under general anesthesia, during which the heart is stopped and blood flow is controlled by a heart-lung bypass machine. Traditional open surgery inflects significant patient trauma and discomfort, and exposes the patient to a number of potential risks, such as an infection, stroke, renal failure, and adverse affects associated with the use of the heart-lung machine, for example.
Due to the drawbacks of open-heart surgical procedures, there has been an increased interest in minimally invasive and percutaneous replacement of cardiac valves. With percutaneous transcatheter (or transluminal) techniques, a valve prosthesis is compacted for delivery in a catheter and then advanced, for example, through an opening in the femoral artery and through the descending aorta to the heart, where the prosthesis is then deployed in the annulus of the valve to be repaired (e.g., the aortic valve annulus). Although transcatheter techniques have attained widespread acceptance with respect to delivery of conventional stents to restore vessel patency, only mixed results have been realized with respect to percutaneous delivery of the more complex prosthetic heart valve.
Various types and configurations of prosthetic heart valves are available for percutaneous valve replacement procedures, and continue to be refined. The actual shape and configuration of any particular prosthetic heart valve is dependent to some extent upon the native shape and size of the valve being replaced or repaired (i.e., mitral valve, tricuspid valve, aortic valve, or pulmonary valve). In general, prosthetic heart valve designs attempt to replicate the function of the valve being replaced and thus will include valve leaflet-like structures. With a bioprostheses construction, the replacement valve may include a valved vein segment that is mounted in some manner within an expandable stent frame to make a valved stent (or “stented prosthetic heart valve”). For many percutaneous delivery and implantation devices, the stent frame of the valved stent can be made of a self-expanding material and construction. With these devices, the valved stent is crimped down to a desired size and held in that compressed state within an outer delivery sheath, for example. Retracting the sheath from the valved stent allows the stent to self-expand to a larger diameter, such as when the valved stent is in a desired position within a patient. In other percutaneous implantation systems the valved stent can be initially provided in an expanded or uncrimped condition, then crimped or compressed on a balloon portion of a catheter until it is as close to the diameter of the catheter as possible. Once delivered to the implantation site, the balloon is inflated to deploy the prosthesis. With either of these types of percutaneous stented prosthetic valve delivery devices, conventional sewing of the prosthetic heart valve to the patient's native tissue is typically not necessary.
In addition to the delivery device itself, typical transcatheter heart valve implantation techniques entail the use of a separate introducer device to establish a portal to the patient's vasculature (e.g., femoral artery) and through which the prosthetic valve-loaded delivery device is inserted. The introducer device generally includes a relatively short sheath and a valve structure.
For example, FIG. 1A illustrates, in simplified form, an introducer device 10 establishing a portal to a patient's vasculature 12, and through which a prosthetic heart valve-loaded delivery shaft 14 (the tip of which is visible in FIG. 1A) has been inserted. As shown, the delivery shaft 14 has been manipulated to locate the loaded prosthetic heart valve 16 (referenced generally) in a desired position relative to an aortic valve 18. An outer delivery sheath 20 contains the prosthesis 16. Thus, in the state of FIG. 1A, the prosthetic heart valve 16 is properly positioned for deployment from the delivery shaft 14 upon proximal retraction of the delivery sheath 20 relative thereto, with a spacing S being established between a distal end of the delivery device's handle 22 and the introducer device 10. As shown in FIG. 1B, an actuator 24 of the handle 22 is moved by the clinician to proximally pull or retract the delivery sheath 20 (as shown by arrow B in FIG. 1B) and release the prosthesis 16.
In light of the above, although there have been advances in percutaneous valve replacement techniques and devices, there is a continued desired to provide different delivery systems for delivering cardiac replacement valves, and in particular self-expanding stented prosthetic heart valves, to an implantation site in a minimally invasive and percutaneous manner.